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Running header: CHARDAKOV METHOD FOR DETERMINING WATER POTENTIAL

Chardakov Method for Determining Water Potential
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CHARDAKOV METHOD FOR DETERMINING WATER POTENTIAL

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Abstract
The purpose of this experiment, Chardokov method, is to provide scientist a quick means to
establishing water potential of a plant tissues. We hypothesized that the water potential of potato
tissue shall be negative ranging from -0.1 to -1.0. The potato tissues mass was recorded and
dipped in solutions with different molarity ranging from 0.1 to 0.8. There was relative change in
density after sometime observed by the sinking of the potato tissues. Calculating the water
potential the results supported our hypothesis by the values being within the range we
hypothesized.

CHARDAKOV METHOD FOR DETERMINING WATER POTENTIAL

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Introduction
In this experiment we are going to use the Chardokov method to determine the water potential of
tissues. This method relies on osmosis which lead to change in density of the plant tissue. This is
due to the effects of the solvents has on the plants tissue. The density of the plant will change
depending on the solvent, the solvent will either cause the plant tissue to gain or lose their
density. In this experiment density changes are observed when the potato tissue sinks or
maintains to float. The water potential is calculated and the result is a negative that should range
from -0.1to -1.0 MPa (Bland and Tanner, 1985). We also applied refraction of light to determine
how deep did the potato tissue sink and this increases the accuracy of the result in this
experiment.
Protocol:
1. Insert 10ml of water or sucrose solution into 9 well labeled test tubes
2. Make 36 uniform tissue sample from a potato using a cork borer. Work quickly to reduce
evaporation and carefully to remove the whole skin
3. Insert 4 tissue samples into each test tube with a solution and ensure that the tissue are
completely submerged I the solution.
4. Let the tissue stay in the solution for 1.5 hours
5. Codify the temperatures in a table
6. Remove a small amount of water dyed with methylene blue using a Pasteur pipet
7. The next step is to insert the pipette in a solution that had tissue sample until the tip is in
the middle of the tube.
8. Carefully release a drop of methylene blue solution and observe if it sinks or floats
9. Codify the readings and repeat the procedure for the remaining test tubes.

CHARDAKOV METHOD FOR DETERMINING WATER POTENTIAL

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Data:

Table 1: Temperature Data – Temperature of the
solutions in which the potato cores were incubated
Temperature (C)
300 c

Temperature (K)
303 k

Table 2: Response of drops (float, sink, hover) when placed in solutions in which potato cores
have been incubated
[Sucrose](molality)

Drop Response

After shakina

0

float

sink

0.1

float

sink

0.2

Sink

sink

CHARDAKOV METHOD FOR DETERMINING WATER POTENTIAL

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0.3

float

Deep sink

0.4

float

Seep sink

0.5

float

0.6

float

0.7

float

0.8

sink

Analysis & Conclusions:

1. Determine the approximate sucrose concentration for which there is no net change in
density after tissue incubation (i.e., drop disperses, the Ψw tissue = Ψw solution).
There is no change in density at the molarity of 0.2. At this point it is observed that after some
absorption it slightly sinks but does not sink deeply. We observed as for lower molarity, that is
0.1 and below, the density of the solution is higher at the beginning but after absorption of
solution the potato tissue ends up sinking after some time. It also happens to higher molarity that
the potato tissue floats at the beginning and sink deeply after some time.
2. Calculate Ψs (= Ψw) in an open system such as a solution in a beaker):
Ψs = -miRT
t=303k
i=1.0
r=0.00831 liter MPa mol-1 K-1
Ψs= 0.0634*1*0.00831*303
=0.1596-3/106
-0.682 MPa.

CHARDAKOV METHOD FOR DETERMINING WATER POTENTIAL

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3. What is the water potential of the potato tuber cells? How does this value correlate to the
expected values? Is this technique accurate? Explain.
The potentials (Ψw) is 0.682 MPa. This value is within the range provided in the lab manual.
Which depicts its level of accuracy to be high as the result obtain from this method are similar to
Chardakov method results.
4. We incubated the cores for about 1.5 hours. How can we determine if this is an adequate
time?
Set up two con...